“Locust wood” can refer to lumber from more than one tree species. In the United States, it most often means black locust (Robinia pseudoacacia) or honey locust (Gleditsia triacanthos). Both are hard, strong woods, but they differ in color, decay resistance, availability, and common uses.
Knowing which species you’re buying matters, especially for outdoor projects. Here’s a practical guide to locust wood and how to choose the right type.
What Is Locust Wood?
Locust wood comes from trees in the Robinia or Gleditsia genera. The two species most often discussed by woodworkers are black locust and honey locust. They are both hardwoods, but their performance is not identical.
Black locust is particularly valued for its heartwood’s resistance to decay and its use in fence posts and other outdoor applications. The U.S. Forest Service also lists black locust for furniture, handles, railroad ties, and fuelwood. USDA Forest Service: Black Locust
Honey locust is a separate species. Its wood is dense, hard, and strong, but it is less commonly available as commercial lumber. The USDA notes its local use for posts, pallets, crating, and general construction. USDA Forest Service: Honeylocust
Black Locust vs. Honey Locust
| Feature | Black locust | Honey locust |
|---|---|---|
| Scientific name | Robinia pseudoacacia | Gleditsia triacanthos |
| Typical heartwood color | Yellowish to golden brown; often darkens with age | Reddish brown |
| Sapwood | Pale and usually distinct from the heartwood | Yellowish and often wider |
| Hardness | About 1,700 lbf on the Janka scale | About 1,580 lbf on the Janka scale |
| Decay resistance | Heartwood is highly decay-resistant | Durable in some uses, but resistance can be more variable |
| Common uses | Fence posts, decking, flooring, handles, furniture | Local construction, posts, pallets, crating, furniture |
| Availability | Regional; can be difficult to source in some areas | Often limited as commercial lumber |
The hardness figures are averages; individual boards vary with growing conditions, moisture content, and the part of the tree they came from. When buying lumber for outdoor use, ask the supplier to identify the species and explain the grade and intended application.
Locust Wood Properties
Hardness and Strength
Both black locust and honey locust are hard, dense woods. Their hardness can help them resist dents and surface wear, but it also makes sawing, drilling, and fastening more demanding than with softer lumber.
Color and Grain
Black locust heartwood ranges from yellowish to golden brown and may darken as it ages. Honey locust typically has reddish-brown heartwood and lighter yellow sapwood. Both may show color variation from board to board, and the grain can be straight or irregular.
Durability
Black locust heartwood is known for strong natural resistance to decay, including in some ground-contact applications. That does not mean every locust board is equally durable: sapwood, poor drying, trapped moisture, and unsuitable installation can reduce service life.
Honey locust is also a hard, strong wood, but it should not automatically be treated as interchangeable with black locust for rot-prone projects. Confirm the species and select lumber intended for the exposure.
Workability
Locust is tough on cutting edges. Sharp tools, steady feed rates, and pre-drilling for screws can help reduce burning, splitting, and tool strain. Grain irregularities can also cause tear-out during planing or shaping.
Common Uses of Locust Wood
Fence Posts and Rails
Black locust is a traditional choice for fence posts because its heartwood can resist decay in soil contact. Post quality, local soil, drainage, and installation all affect how long a fence lasts.
Decking and Outdoor Projects
Black locust may be used for decking, steps, garden structures, and other outdoor projects. Its hardness and natural durability are useful, but boards need proper installation and inspection as they weather. Honey locust may also be used outdoors when the project and lumber grade are appropriate.
Flooring
The hardness of locust makes it a potential flooring material for areas that receive regular use. Its color and grain give floors a distinctive appearance. Because the lumber may be difficult to machine and is not always easy to source, check availability and installation requirements before choosing it.
Furniture and Woodworking
Locust can be made into furniture, turned objects, tool handles, and other durable items. Its color variation can be attractive, though the hardness and irregular grain may require more careful machining and finishing.
Pallets, Crates, and General Construction
Honey locust is used locally for pallets, crating, posts, and general construction. These uses depend on regional availability and the quality of the lumber.
Firewood
Locust is dense and can make useful firewood when properly seasoned. Allow it to dry thoroughly before burning, and use only clean, untreated wood in an appliance designed for wood burning.
Advantages of Locust Wood
- Hard and strong: Suitable for projects that need a tough, wear-resistant material.
- Naturally durable black locust heartwood: Can be a good option for certain outdoor and ground-contact uses.
- Distinctive appearance: Golden or reddish-brown tones can add character to furniture and flooring.
- Several practical uses: Depending on species and local supply, locust may be used for posts, decking, flooring, furniture, handles, and firewood.
Limitations to Consider
- Species names can be confusing: “Locust” does not identify one specific wood. Confirm whether the lumber is black locust or honey locust.
- Difficult to machine: Its hardness can require sharp, durable tools and careful cutting.
- Availability varies: Locust lumber is not stocked everywhere, and board sizes or grades may be limited.
- Drying and movement matter: Poorly dried lumber can crack, warp, or move after installation.
- Sourcing has local ecological context: Black locust is native to parts of eastern North America but can spread aggressively outside its native range. Consider local sourcing and regional guidance when choosing material.
Working with Locust Wood
Check that the lumber is properly dried before building, and allow it to acclimate to the project environment. Use sharp blades and bits, make test cuts if the grain is irregular, and pre-drill for screws to reduce splitting. For outdoor projects, design to shed water rather than trap it, and follow the finish manufacturer’s instructions if you choose to apply a coating.
Frequently Asked Questions
Is locust wood a hardwood?
Yes. Black locust and honey locust are both hardwoods from broadleaf trees.
Is black locust the same as honey locust?
No. Black locust is Robinia pseudoacacia, while honey locust is Gleditsia triacanthos. Their appearance and decay resistance differ, so the names should not be used interchangeably when selecting lumber.
Is locust wood good for outdoor use?
Black locust heartwood is especially valued for outdoor uses such as fence posts. Honey locust may also be used for some exterior projects, but confirm the species, grade, and suitability for the expected exposure.
Is locust wood difficult to work with?
It can be. Locust is hard and dense, so sharp tools, careful machining, and pre-drilling are helpful.
Is locust wood good firewood?
Yes, seasoned locust can be used as firewood. Make sure it is dry before burning and never burn painted, treated, or contaminated wood.
Conclusion
Locust wood is a broad name that most often refers to black locust or honey locust. Both are hard, strong woods, but black locust is particularly known for its durable heartwood and use in outdoor posts. Honey locust is also useful, though it is less common as commercial lumber. Identify the species before buying, match the wood to the project, and account for its hardness when working with it.